Uniqueness of the limit cycles of quadratic systems with a second-order weak focus. (Chinese. English summary) Zbl 1024.34023
Summary: The author proves that the plane quadratic system has at most one limit cycle surrounding a second-order weak focus, and that if the product of the second and the third focus value of the weak focus is positive definite, then the system has no limit cycle surrounding the second-order weak focus.
MSC:
| 34C05 | Topological structure of integral curves, singular points, limit cycles of ordinary differential equations |
